isolate POSIX builds from the host UCRT, wire lwext4 and ntfs-3g as ext4.sys and ntfs.sys, split the FAT driver into directory/file/async/driver/mount units, add posixsrv and dwm plus input/console/desktop syscall clients and a pile of new smoke targets, rename serial.sys to cereal.sys, name HDA/USB/lwIP/AHCI workers, harden ATA probing/reset/removal around actual hardware deadlines, absent-channel detection, diagnostics and explicit worker lifetime, redo ACPI S5 shutdown around GAS/MMIO and HW-reduced firmware, scan SSDTs for _S5 and deal with Intel SMI sleep trapping, make serial and SMP timeouts use real monotonic deadlines, add thread names and fix terminal thread teardown, scheduler and APC prepare/commit races, make advisory file locks queryable and preserve split ranges and add mutable file append state, add shared-memory pipes with kernel-assisted wait/wake, introduce capability-scoped input and display managers, split surface map rights into read/write, add explicit unmap and replace present with commit/generation/damage tracking while keeping physical presentation under the display manager, decouple native exception classes from Win32 exception numbers and translate them in kernel32, add opaque process startup data, bump the resource protocol to v3 with namespace directories, symlinks and enumeration and service control to v2 with generic READY handle exports, add the new POSIX errno/status surface and rebuild fds around posixsrv-owned shared open descriptions, descriptor-local flags, exact inheritance snapshots, dup/fcntl/record locks and shared-ring pipes, add waitpid, POSIX credentials/groups/sessions/passwd/group lookups and move sockets onto stable open descriptions, port the shells and apps to the new console/input services and surface commit API, teach init to load services.ini and start/supervise RSSRV, DWM and generic services under restricted capabilities while publishing their endpoints through RSSRV, split RSSRV into namespace, volume, display, session, input, console and resource components and make /SystemRoot a real symlink to the independently published system volume, shift the syscall table again, expand lock/resource/surface/POSIX/service/thread smoke coverage, make docs scream ASK QUESTIONS and DISCUSS at LLMs, replace MIT No Attribution with WTFPL+.

code/user/tests/posix_pipe_smoke/posix_pipe_smoke.c

@@ -0,0 +1,121 @@
+// User-mode smoke test for POSIX pipe, nonblocking, and poll semantics.
+
+#include <string.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <poll.h>
+#include <sys/stat.h>
+
+// Writes one NUL-terminated diagnostic to stdout.
+static void print(const char* text) {
+    (void)write(1, text, strlen(text));
+}
+
+// Terminates the smoke test with one diagnostic.
+static void fail(const char* message) {
+    print("posix_pipe_smoke: ");
+    print(message);
+    print("\n");
+    exit(1);
+}
+
+// Requires one descriptor to expose the expected immediate poll bits.
+static short poll_now(int fd, short events) {
+    struct pollfd descriptor;
+    descriptor.fd = fd;
+    descriptor.events = events;
+    descriptor.revents = 0;
+    int result = poll(&descriptor, 1, 0);
+    if (result < 0)
+        fail("poll failed");
+    return descriptor.revents;
+}
+
+// Runs pipe lifetime, readiness, EOF, broken-pipe, and atomic-write checks.
+int main(void) {
+    int descriptors[2];
+    if (pipe(descriptors) != 0)
+        fail("pipe failed");
+
+    struct stat st;
+    if (fstat(descriptors[0], &st) != 0 || !S_ISFIFO(st.st_mode))
+        fail("read endpoint is not FIFO");
+    if (fstat(descriptors[1], &st) != 0 || !S_ISFIFO(st.st_mode))
+        fail("write endpoint is not FIFO");
+
+    if (poll_now(descriptors[0], POLLIN) & POLLIN)
+        fail("empty pipe reported readable");
+    if (!(poll_now(descriptors[1], POLLOUT) & POLLOUT))
+        fail("empty pipe write endpoint not writable");
+
+    if (write(descriptors[1], "abc", 3) != 3)
+        fail("basic write failed");
+    if (!(poll_now(descriptors[0], POLLIN) & POLLIN))
+        fail("pipe data did not become readable");
+
+    char buffer[4] = {0, 0, 0, 0};
+    if (read(descriptors[0], buffer, 3) != 3 || strcmp(buffer, "abc") != 0)
+        fail("basic read failed");
+
+    if (fcntl(descriptors[0], F_SETFL, O_NONBLOCK) != 0)
+        fail("read F_SETFL O_NONBLOCK failed");
+    errno = 0;
+    if (read(descriptors[0], buffer, 1) != -1 || errno != EAGAIN)
+        fail("empty nonblocking read did not return EAGAIN");
+
+    int writerAlias = dup(descriptors[1]);
+    if (writerAlias < 0)
+        fail("writer dup failed");
+    if (close(descriptors[1]) != 0)
+        fail("close original writer failed");
+    if (poll_now(descriptors[0], POLLIN | POLLHUP) & POLLHUP)
+        fail("HUP published before final writer closed");
+    if (close(writerAlias) != 0)
+        fail("close final writer failed");
+
+    short eofEvents = poll_now(descriptors[0], POLLIN | POLLHUP);
+    if ((eofEvents & (POLLIN | POLLHUP)) != (POLLIN | POLLHUP))
+        fail("EOF readiness transition missing");
+    if (read(descriptors[0], buffer, 1) != 0)
+        fail("final writer close did not produce EOF");
+    if (close(descriptors[0]) != 0)
+        fail("close read endpoint failed");
+
+    if (pipe(descriptors) != 0)
+        fail("second pipe failed");
+    if (close(descriptors[0]) != 0)
+        fail("close second read endpoint failed");
+    errno = 0;
+    if (write(descriptors[1], "x", 1) != -1 || errno != EPIPE)
+        fail("write without readers did not return EPIPE");
+    if (close(descriptors[1]) != 0)
+        fail("close broken writer failed");
+
+    if (pipe(descriptors) != 0)
+        fail("atomic pipe failed");
+    if (fcntl(descriptors[1], F_SETFL, O_NONBLOCK) != 0)
+        fail("write F_SETFL O_NONBLOCK failed");
+    char atomic[PIPE_BUF];
+    memset(atomic, 'A', sizeof(atomic));
+    for (;;) {
+        errno = 0;
+        ssize_t written = write(descriptors[1], atomic, sizeof(atomic));
+        if (written == (ssize_t)sizeof(atomic))
+            continue;
+        if (written == -1 && errno == EAGAIN)
+            break;
+        fail("PIPE_BUF write was partially committed");
+    }
+    if (poll_now(descriptors[1], POLLOUT) & POLLOUT)
+        fail("full pipe still reported writable");
+    if (!(poll_now(descriptors[0], POLLIN) & POLLIN))
+        fail("full pipe read endpoint not readable");
+
+    if (close(descriptors[0]) != 0 || close(descriptors[1]) != 0)
+        fail("atomic pipe close failed");
+
+    print("posix_pipe_smoke: PASS\n");
+    return 0;
+}